apacite bibliographystyle and footnote citationsPlease pare down your code to focus on what's relevant for your question. Surely you don't need to provide the entire title page and the names of all the chapters, right? What's currently missing are the citation commands you would like to use. Please edit your code to provide what's relevant.

Specifying various fonts with various scales with fontspec@SadeqDousti - I'm not sure I understand your objective. Do you maybe mean something like \setmainfont[BoldFeatures={Scale=0.8}, BoldFont = {TeX Gyre Heros Bold}]{TeX Gyre Pagella}? This will use a scaled version of Heros for bold material, and Pagella for everything else. Please advise.